Showing papers on "Evaporation (deposition) published in 1985"

Properties of CeO2 thin films prepared by oxygen-ion-assisted deposition.

Abstract: Thin films have been prepared by electron-beam evaporation of CeO2, where the growing film has been bombarded with oxygen ions. The packing density of the films has been increased from ∼0.55 without ion bombardment to unity with bombardment as determined by moisture adsorption measurements. The refractive index, extinction coefficient, and scattering loss are reported for a range of ion energies from 50 to 1200 eV. The ratio of ion-current density to film growth rate required to produce films that did not adsorb moisture was found to be a minimum for ion energies in the 300–600-eV range. Absorption and scatter losses are smallest for the lower ion energies and the crystal structure of CeO2 films is relatively stable under ion bombardment although ion-assisted films tend to be less crystalline than evaporated layers.

Silver particles on stochastic quartz substrates providing tenfold increase in Raman enhancement

Abstract: Exceptionally strong Raman enhancements have been observed for molecules adsorbed on silver deposited onto etched quartz substrates. A stochastic arrangement of tall quartz posts, with an average spacing of approx. 110 nm, is obtained by plasma etching of SiO/sub 2/ using a silver island film as an etch mask. Silver particles are produced by angle evaporation. Raman enhancment for adsorbed p-nitrobenzoic acid is maximized by optimizing the deposition parameters, which results in a tenfold enhancement compared to island films and crossed-grating structures. Observation of signals from several polyaromatic molecules demonstrates that the surface provides strong Raman enhancement for a variety of adsorbates. 30 references, 3 figures, 2 tables.

Epitaxial growth of (100)CdTe on (100)GaAs induced by pulsed laser evaporation

Abstract: Epitaxial (100) CdTe films were grown on the (100) GaAs surface by pulsed laser evaporation. The growth was achieved on substrates held at 260 °C and under a pressure of about 8×10−8 Torr. High‐energy electron diffraction, x‐ray diffraction, and UV reflectivity studies have shown that epilayers of high crystalline quality were obtained. The surface morphology of films thicker than about 0.4 μm approached atomic smoothness. No incorporated impurities, including oxygen and carbon, were found by Auger electron spectroscopy in the films studied.

Studies on e-beam deposited transparent conductive films of In2O3: Sn at moderate substrate temperatures

Abstract: An electron beam evaporation method is used to prepare In2O3 films with and without Sn doping. It is shown that highly transparent and conducting films can be prepared at substrate temperature as low as 200 degrees C. The characteristic feature of such films is their high carrier density and high infrared reflectivity. The lowest resistivity is found to be 2.4*10-4 Omega cm with a carrier concentration of 8*1020 cm-3 and mobility of about 30 cm2 V-1 s-1 at the doping level of 4 mol.% SnO2. These polycrystalline films show a highly preferred orientation. On the basis of Hall measurements and structural data, sources of scattering in these films are suggested.

Tc depression in thin Nb films

Abstract: The depression of Tc has been studied as a function of Nb film thickness which ranged from 15 A to 1500 AIt is seen that Tc of the bulk Nb (1500 A) is very sensitive to evaporation parameters including the residual gases in the evaporator, evaporation rate, and substrate temperature Depending on the conditions of deposition, we observe different Tc fall-off as a function of thickness and R□ We attribute the different fall-offs vs thickness to three main mechanisms including proximity effect, bulk resistivity effect and localization The relative strength of each mechanism can be controlled by deposition parameters

Nitride film formation by ion and vapour deposition

Abstract: Boron nitride coating films were produced using ion beams of nitrogen molecules with energies 25–40 keV and simultaneous evaporation of boron (IVD method) and were analysed by infrared absorption spectra. X-ray diffraction and electron microscopy. Films with the composition ratio B N larger than about 0.9 have structures of cubic BN or close to this. Those with smaller B N than about 0.9 consist of hexagonal (layered) boron nitride or close to this. On some films, well oriented wurtzite type crystal was observed. A depth analysis for a titanium nitride film deposited on stainless steel prepared by IVD indicates the presence of a thick mixed layer of film and substrate.

Thin-film deposition by laser-assisted evaporation.

Abstract: Laser-assisted evaporation of materials has several unique features and is being used increasingly as a thin-film deposition process. Characteristics of this technique and design parameters of a laser-assisted evaporation system are discussed. Types of source material, scanning and focusing of the laser beam, optical elements to deliver laser power to the sources, and emplacement of these elements to deposit thick films are explained.

Coevaporation with a rate control system based on a quadrupole mass spectrometer

Abstract: In a deposition system designed for coevaporation, the control of the individual evaporation rates is the crucial point. This paper describes a deposition system where the evaporation rates of three resistively heated elemental sources are controlled by utilizing a quadrupole mass spectrometer. The rate monitoring and control system is characterized for the case of CuInSe2 deposition, where it is shown that a precise control of the properties of the deposited film can be achieved. The results reported are of general interest, and neither restricted to three elements nor to the specific elements used in the case studied.

MOS hydrogen sensors with ultrathin layers of palladium

Abstract: MOS gas sensors were fabricated on n- and p-type silicon (5-7 Ω. cm) with thermal oxide layers ranging in thickness from 66 to 269 A. A layer of palladium 30 A thick was deposited through an evaporation mask. A layer of gold 350 A thick was deposited over the palladium to provide a continuous electrical contact. Measurements were made of the capacitance at 1 MHz as a function of gasambient and time. The devices showed sensitivity to hydrogen at room temperature. Compared to devices fabricated with 300-A layers of palladium, the thin film devices showed much faster response and recovery at room temperature and reduced magnitude of response. Devices fabricated on p-type silicon were noticably faster than those fabricated on n-silicon. First-order reaction kinetic fits showed general agreement with the data.

Structure and short-range order of vapour-deposited Si1−xSnx amorphous alloys

Abstract: Amorphous Si1−x Snx alloy films have been prepared by the simultaneous evaporation of Si and Sn in high vacuum onto various substrates held at liquid nitrogen temperature The structure of the alloys was investigated using scanning high-energy electron diffraction, density measurements and Mossbauer spectroscopy For x<0·5, Sn atoms are shown to be substituted for Si, and selectively surrounded by Si atoms in almost perfect tetrahedral units, in a random continuous network This trend of the alloys towards order can be traced to the size difference between Si (d = 2·35 A) and Sn (d = 2·80 A)

Summary Abstract: Properties of ion plated oxide films

Abstract: Films of sio, AlzOJ, z-o, rs,o; and Ti02 on unheated glass and steel substrates were prepared by reactive ion plating starting from molten metals. Coating was performed in a modified Balzers BAK 760 box coater. For evaporation, an electron beam evaporator with a positive crucible functioning as the anode for a low voltage ion souree was used.1•2 In this way during evaporation an appreciable amount of coating material ions 1Vereformed. The substrates were mounted at an electrically insulated holder. Immersed into the plasma, they received a negative self-biasing potential of a few tens of volts which was sufficient for plating. J Electron diffraction experiments on deposits made in this deviee showed that with the exception of'the glassy SiOz films all other films had an extremely fine grained and highly disordered polycrystalline structure. Transmission electron microscopy (TEM) and secondary emission microseopy (SEM) investigations of the film surface and cross section as well as sorption experiments with water vapor showed a smooth film surface and a very compact and dense film microstructure. In this respect ion plated films appeared to be similar to plasma sputtered films, whereas reactively evaporated films were found to be less dense and had a coarser morphology. This can be seen in Figs. land 2. Ion plated oxide films were fully oxidized and showed in their high transmittance range no absorption detectable with intensity measurement methods. A remarkable property was their refractive index. As a consequence of the dense microstructure, the Indices ofthe films were very near to that ofthe corresponding bulk materials as can be seen in Table 1. Plasma diode sputtered films showed similar results." High rate planar magnetron sputtered films, however, may show lower refractive index values! due to the lower discharge voltage and lower partiele energy in this deposition process. Low particle energy is also responsible for the low index values found with evaporated films. Substrates are

Coating for optical devices

Abstract: Disclosed is a device including a surface coating for passivation or anti-reflection, and a method of manufacture. The coating comprises ZrO2 doped with yttrium, magnesium or calcium. The doped ZrO2 is preferably deposited on the device surface by electron-beam evaporation from a single crystal source of ZrO2 and Y2 O3, MgO or CaO.

Formation of low defect density SiOx films for Josephson integrated circuits

Abstract: SiOx films deposited by evaporation under oxygen atmosphere were investigated to form low defect density insulating layers in Josephson integrated circuits. The defect density is high in SiOx films deposited under an oxygen pressure of less than 1.33×10−3 Pa, but it decreases greatly in films deposited under higher oxygen pressure. This can be explained by the presence or absence of elemental Si in the films. Elemental Si is present in films deposited under low oxygen pressure, but not in films deposited under higher oxygen pressure. The insulating characteristics of a SiOx film deposited under an oxygen pressure of 1.33×10−2 Pa are excellent.

Investigation of UV-laser induced metallization: Platinum from Pt (PF 3 ) 4

Abstract: We have measured the Pt deposition yields on various substrate materials from Pt(PF3)4 in the case where a KrF laser irradiates the solid surface. The data imply that an ample amount of electrons is produced by the laser surface interaction and dissociative electron capture initiates the metal deposition. The metal atom release is completed by a concerted surface reaction at a reduced energy demand. This is evidenced by thermochemical considerations. A simple criterion is derived to estimate the attainable spatial resolution. Sudden melting and evaporation beyond a certain layer thickness interferes with the deposition process. This is in accord to a model given, based on a poor thermal contact at the platinum substrate interface. The results may help to optimize uv laser induced metal deposition with respect to purity, adherence and structure.

Infrared detecting element

Abstract: PURPOSE:To provide an IR detecting element having a small size and high sensitivity and to easily manufacture said element by forming an IR sensor and thin film transistor on the same substrate and using a pyroelectric material film as a gate oxide of the thin film transistor. CONSTITUTION:A lower electrode 2 consisting of Pt is formed by a sputtering method on the substrate 1 consisting of an MgO single crystal obtained to a specular surface and the thin pyroelectric material film 3 is formed thereon. The upper electrode 4 consisting of NiCr is deposited by evaporation thereon. A thin CdSe film doped with In or the like to be made into an n-type is then deposited by evaporation as a semiconductor layer 6 thereon. A source electrode 5 and a drain electrode 7 are finally deposited by evaporation on said layer to form the IR detecting element. An aperture 8 is provided to the substrate 1 in the part corresponding to the electrode 4, i.e., the part operating as the pyroelectric type IR detecting part.

Ferromagnetic films for high density recording and methods of production

Abstract: A ferromagnetic film for magnetic recording comprises a copper substrate having particles of iron and iron oxides dispersed in the surface layer of the copper. The particles have maximum dimensions in the range between 50 and 500 Angstroms. The ferromagnetic film can be formed by ion implantation of iron ions into the copper substrate followed by heat treatment to permit growth of ferromagnetic particles to the desired size. As an alternative to ion implantation, the iron can be deposited on the copper substrate by sputtering or evaporation and mixed with the copper by ion beam mixing.

Photochromic evaporated films of spiropyrans with long alkyl chains

Abstract: Organic thin films consisting of spiropyrans with long alkyl chains were prepared by evaporation. These films crystallized immediately or gradually in an ambient atmosphere. It has been demonstrated that introduction of long alkyl chains is an effective way to obtain transparent and smooth films by evaporation and that reversible photo-isomerization, a kind of on-off switching, is performed in the films.

Acoustic transducers utilizing ZnO thin film

Abstract: In an acoustic transducer comprising a lower electrode, a zinc oxide (ZnO) film, which is a piezo-electrically active body, and at least one upper electrode superposed one after another on a substrate, the lower electrode consists of at least one gold polycrystalline film deposited by evaporation, interposing a thin chromium film, on the substrate and crystallites of the gold polycrystalline film are so oriented that the standard deviation of the locking curve for the (111) diffraction beam is smaller than 3°. In order to obtain a gold film having such a good orientation, the thickness of the chromium film is limited to 20 nm at largest. The zinc oxide film thus superposed on the lower electrode thus composed is excellent in c-axis orientation and thus permits to obtain a high electro-mechanical coupling factor efficiency of the acoustic transducer.

Method of controlling deposition amount distribution in a vacuum deposition plating

Abstract: In a continuous vacuum deposition plating of a metal strip, thinner coating at the edges can be prevented by maintaining the pressure of the deposition chamber in which an evaporation chamber is housed at a properly higher level than the pressure of the evaporation chamber.